:In a similar way, I'm removing interrupt mask copies in memory. We :still mask interrupts which aren't in use, but no others. If anybody :has any reason not to want to do this, we should talk about it. : :Greg

I think you still have to mask level interrupts, otherwise you won't be able to sti. Some subsystems may generate a phenominal number of interrupts while the interrupt routine is running -- for example, the serial ports. I think the masking was put in there as an optmiization not only for that, but also so the interrupt could be EOI'd early so as to allow a new interrupt to become pending while the interrupt routine was running (thus closing a potential window of opportunity where an interrupt might otherwise be missed).

If you remove the masking you have to delay the EOI and that is probably a huge mistake because it may lead to lost interrupts. Another example: if a keyboard interrupt is lost you can lose the keyboard entierly. If the EOI is delayed there is a much greater chance of losing the keyboard interrupt.

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